1. Field of the Invention
This invention generally relates to a touch control device and, more particularly, to a projective capacitive touch sensor.
2. Description of the Related Art
With the popularity of the portable device, human-machine interface devices have been broadly adapted to portable devices, such as PDAs, cell phones and note books so as to humanize the operation thereof. And the touch screen plays an important role in humanize operation.
Presently, touch screens can mainly be divided into resistive, capacitive, infrared and SAW touch screens. Because the projective capacitive touch screen will not be deteriorated by moisture and the material of its touch surface has no function in touch detection mechanism, it is more suitably adapted to portable devices operated outdoors.
The projective capacitive touch screen mainly detects the capacitance variation of a touch-sensor pad induced by a conductive object approaching thereto so as to detect a position of the conductive object with respect to the touch screen. For example FIG. 1 shows a sensor array 9 of a conventional touch-sensor pad that includes a plurality of first sensor elements 91 coupled together, a plurality of second sensor elements 92 coupled together and a processing device 93, wherein the first sensor elements 91 and the second sensor elements 92 are coupled to the processing device 93 through conductive traces. The first sensor elements 91 and the second sensor elements 92 are disposed in a repetitive sequence on the sensor array 9 along a moving direction of the conductive object. The processing device 93 respectively calculates capacitance variations of the first sensor elements 91 and the second sensor elements 92 so as to identify a two-dimensional position of the conductive object approaching the sensor array 9. However, the sensor array 9 has a double layer structure thereby requiring more complicated process during manufacturing. Details of the sensor array 9 above can be referred to U.S. Patent Publication No. 2008/0007534.
Accordingly, it is necessary to provide a projective capacitive touch sensor having a single layer of sensing units so as to simplify the manufacturing process thereof.